Field of the Invention
The present invention relates to a classifying method of classifying an article into one of a plurality of groups, a storage medium, an inspection method, and an inspection apparatus.
Description of the Related Art
As an apparatus for performing visual inspection or internal inspection of an article, there is provided an inspection apparatus for performing inspection using an image (target image) obtained by capturing the article by an image capturing unit. The inspection apparatus performs so-called “learning” of determining an evaluation method for obtaining the evaluation value of an image, by using the images (learning images) of a plurality of samples each of which has already been classified into one of a plurality of groups. An evaluation value for the image of the article is obtained based on the determined evaluation method, and the article is classified into one of the plurality of groups based on the obtained evaluation value. Therefore, the inspection apparatus may determines an evaluation method by learning so as to improve the performance of classifying an article.
Patent literature 1 (Japanese Patent Laid-Open No. 2010-102690) proposes a method of determining a combination of feature amounts to be used by an evaluation method by using a plurality of learning images. Furthermore, patent literature 2 (Japanese Patent Laid-Open No. 2010-157154) proposes a method in which a sample that has been classified into different categories by an apparatus and a user is specified, and the user is prompted to change an evaluation method so that the sample is classified into the same category by the apparatus and the user.
In the method described in patent literature 1, for example, if a plurality of learning images include an image with a small defect, a low-contrast defect, or the like, an evaluation method may not be determined so as to classify a sample associated with the image into a group into which the sample should be originally classified. In this case, patent literature 1 does not describe a technique of changing the evaluation method so as to improve the performance of classifying an article.
In the method described in patent literature 2, since a sample which has been classified into different categories by the apparatus and the user is specified, it is necessary to make the apparatus classify all samples every time the evaluation method is changed. This may complicate a process (learning process) of determining an evaluation method to be used to classify an article. In addition, in the method described in patent literature 2, the user is prompted to change a feature amount to be used by the evaluation method based on the feature amount distribution of a category into which each of the apparatus and the user has classified a sample. The skill of the user is required to change the evaluation method. As the number of selectable image features increases, determination by the user becomes more difficult, thus requiring considerable time to perform determination.